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    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    <script>
        // 邮箱以这些结束.com|.cn|.sina|.net
        var reg = /^\d{3,12}@(qq|163|126)\.(com|cn|sina|cn)$/
        var str = '12345@163.com'
        console.log(reg.test(str))
    </script>
</body>

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